Epidemiologic studies are conducted to identify life-style and environmental risk factors for cancer and to investigate their interrelationships with genetic determinants of these diseases. Case-control studies of non-Hodgkin's lymphoma, multiple myeloma, leukemia, mesothelioma and cancers of the lung, brain, bladder, stomach, liver, prostate, pancreas and head and neck are in progress. A large multi-center investigation is examining risk factors for malignant neoplasms among subjects being screened for cancers of the prostate, lung, colon, rectum, and ovaries. Another large prospective study is being carried out among women in Shanghai, China. In a case-control investigation in Puerto Rico, a higher rate of increase in the risk of oral cancer per additional alcoholic drink was found among persons with the ADH31-1 genotype compared to other variants at this locus. Subjects with the ADH31-1 genotype efficiently metabolize alcohol to acetaldehyde, implicating this latter compound in oropharyngeal carcinogenesis. Cooking practices which lead to the production of heterocyclic amines were linked to increased risk of adenocarcinoma of the stomach and green tea consumption was linked to decreased risk for colorectal and pancreatic cancer. Tobacco use and sunlight exposure were explored as potential risk factors for non-Hodgkin's lymphoma and an investigation of childhood risks for cancer found an association with paternal cigarette use.